scripts: trace_capture_usb: disable tracing on exit

Disable tracing on exit and do not discard data immediately after
enabling tracing. The length of the data depends on the timings of the
host and targets and may simply be an arbitrary length that does not fit
any trace format or frame.

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>

Author: jfischer-no

scripts/tracing/trace_capture_usb.py

@@ -82,10 +82,6 @@ def main():
     #enable device tracing
     write_endpoint.write('enable')
 
-    #try to read to avoid garbage mixed to useful stream data
-    buff = usb.util.create_buffer(8192)
-    read_endpoint.read(buff, 10000)
-
     try:
         with open(output_file, "wb") as file_desc:
             while True:
@@ -96,6 +92,7 @@ def main():
     except KeyboardInterrupt:
         pass
     finally:
+        write_endpoint.write('disable')
         print('Data capture interrupted, data saved into {}'.format(args.output))
         usb.util.release_interface(usb_device, interface)